Top 10 Best Third Party Pentax Fit Lenses 2018

If you’re a Pentax camera owner who has some cash to splash on a new lens, our top ten list of Pentax K-Mount third-party lenses should make it a little easier for you to decide which lens to buy.

Third-party lenses are simply ones that aren’t made by the same company that made your camera but when purchased in the correct mount, will fit your camera of choice. So, the ten lenses listed here will fit the full line-up of Pentax DSLRs, including the Pentax KP, Pentax K-70 and Pentax K-1.

As well as third-party lenses, we’ve also got a guide to the best 26 Pentax lenses you can buy to date and a feature which looks at the range of lenses available for the Pentax K-1 so you can make a more informed choice when purchasing a new lens.

If you don’t see your favourite lens here that’s probably because we’ve not reviewed it for it didn’t score high enough to make the top ten but please do add your comments below on lenses you’d like us to review and we’ll do our best to oblige.

1. Venus Laowa 12mm f/2.8 –

The Venus Laowa 12mm f/2.8 is a unique lens that’s well made, with extraordinary performance. There are those who will struggle with the manual focus, but there are solutions to this with various techniques. There’s no doubt that the lens performs exactly as claimed and should give excellent service for a very long time. The Laowa 12mm f/2.8 is a unique ultra-wide lens that delivers its promise of high quality and minimal distortion.

2. Irix 15mm f/2.4 –

The Irix 15mm f/2.4 lens is a powerful photographic tool. This lens from Irix lifts the performance for such lenses way beyond the first early 1970s offerings and gives us a lens that is free from flare, and very sharp. This Swiss design is an excellent one, built in Korea to very high standards. Overall, the Irix 15mm f/2.4 is a beautifully engineered lens that produces beautiful images.

3. Irix 11mm f/4 Firefly

What an exciting lens the Irix 11mm f/4 Firefly is. It opens up a whole new world of creative possibilities in a well-made, well-designed package that delivers the image quality. It will not be for everybody, perhaps because of the ultra-wide style of the images, or maybe because of difficulties using the manual focus system, but if the lens appeals to the individual photographer’s creativity then it will be a rewarding experience. The Irix 11mm f/4 Firefly is the widest ultra-wide rectilinear lens, full of exciting creative possibilities.

4. Samyang (Rokinon) 20mm f/1.8 ED AS UMC –

20mm lenses are very attractive for the wide angle photographer, wide enough to be interesting, but not so wide as to be very difficult to handle. We have here a lens that is well made, has a very high standard of performance, and a reasonable price tag. Without a doubt, the Samyang 20mm f/1.8 ED AS UMC adds up to being a very good deal.

5. Laowa 105mm f/2 T3.2 Smooth Trans Focus –

Laowa certainly knows how to make exciting and different lenses. It’s always good to see lenses that go beyond the pure technicalities, offering some unique “feel” or “character” to images. The Apodization filter is very clever, it works and the bokeh offered is indeed superb, whilst the sharpness of the main subject is not compromised in the slightest.

Despite some handling inconvenience, the Laowa 105mm f/2 T3.2 is fun to use and a challenge to become proficient with. It may not be for everyone, but for those willing to get to grips with it the reward will be in that sublime, creamy smooth bokeh.

6. Samyang 135mm f/2 ED UMC –

Those interested in a fast 135mm, who are either on a budget or don’t need autofocus for their work, should certainly consider this lens. It’s more than capable of delivering sharpness on a par with high-end lenses, but at a fraction of the cost. This, coupled with the excellent build quality and smooth manual focus action make the Samyang 135mm f/2 ED UMC lens an excellent buy overall.

7. Samyang 12mm f/2.8 ED AS NCS Fish-eye –

At face value, this 12mm fisheye lens from Samyang would be good value if it was only half-decent, due to the low price and excellent build quality. The fact it is capable of producing images with outstanding sharpness and offers a unique stereographic projection means that this lens should be high on the wishlist of anyone looking for a diagonal fisheye for their full-frame DSLR.

8. Sigma 18-300mm f/3.5-6.3 Macro OS HSM C –

This lens is certainly capable of delivering images with decent sharpness. It is reasonably compact, well built and the price is very reasonable too. Those looking for a lens covering a wide range of focal lengths, whilst allowing them to travel light should certainly give this lens serious consideration. The Sigma 18-300mm f/3.5-6.3 Macro OS HSM C is capable of delivering images with decent sharpness and is reasonably priced.

9. Laowa 15mm f/4 1:1 Macro –

This is a very versatile lens with some unique features for the focal length. It has commendably high central sharpness and very low levels of CA. Distortion and vignetting are high and edge sharpness suffers. In the right hands, the Laowa 15mm f/4 should produce some excellent dramatic images, all at a fairly modest price level. Performance is better on APS-C format cameras. The Laowa 15mm f/4 1:1 lens is a versatile optic offering unique features for an ultra-wide.

10. Samyang 8mm f/3.5 UMC Fish-Eye CS II –

Even if you discount the fact that this 8mm fisheye is a high-quality lens, available for under half the price of equivalents from other manufacturers, this is a very interesting lens. It is capable of producing images with excellent sharpness, the build quality is good, and the removable hood adds extra flexibility, allowing the lens to be used as a partial circular fisheye on full frame cameras. Even the lack of autofocus shouldn’t put you off this lens, as the depth of field available with a fisheye, makes focusing manually incredibly easy.